Extractors & fuses

[Octopus]

All

I attended the Elecsa update in Woking last night - useful as it was there was one "thing" that stood out was their emphasis on extractor fans being fused down to the "manufacturers instructions".

So given that 90%+ of fans suggest fusing down to 3A, and given that most will need live and switched live, and (as far as I know) there is no such thing as a fan isolator switch with 2 fuses in it, how do other members deal with this?

Most cowboy installs seem to ignore the requirement for an isolation switch anyway.

 

[pushrod]

I always fit a fuse on the permant live as well as the 3 pole isolator.

Boss always moans at me.

On a similar vain alot of boilers want fusing to 3A and a two pole isolating switch, so a standard switched fuse spur is no good. (I still fit the switched fuse spur).

MK do a DP switched FCU :smile5:

 

[D Skelton]

Most cowboy installs seem to ignore the requirement for an isolation switch anyway.

What requirement for an isolation switch?

Edit: By that I mean a local 3 pole isolation switch, not isolation in general.

 

[Sickmick]

The story I heard (could have been scare tactic) from 2 different NIC assessors, was that this issue had already been before a court. A fault had developed that lead to a fire on a fan unit, which had been wired via the traditional 3 pole fan isolator from the 6 amp lighting circuit. Manufacturer said it wouldn't have happened if their instructions had been followed, and the court agreed and since BS7671 says follow manufacturers instructions the electrician was found to be at fault. Since hearing that I've always followed the wiring diagram in the instructions, there's a couple of configurations they suggest, either fuse the light or install seperate pull switch for the fan.

 

[D Skelton]

I would bet money on that being a scare tactic. If the fan was wired in on a 6A lighting circuit a reasonable assumtion can be made that the circuit was protected by a 60898. I fail to see what type of fault could occur that could cause a fire if the circuit was protected by a 6A MCB unless it was the wiring at fault. Also, if the manufacurers instructions are saying to fuse down to 3A, I fail to see the logic as a 6A 60898 would trip long before a 3A 1362 even begins to think about blowing.

 

[Johnny-G]

The story I heard (could have been scare tactic) from 2 different NIC assessors, was that this issue had already been before a court. A fault had developed that lead to a fire on a fan unit, which had been wired via the traditional 3 pole fan isolator from the 6 amp lighting circuit. Manufacturer said it wouldn't have happened if their instructions had been followed, and the court agreed and since BS7671 says follow manufacturers instructions the electrician was found to be at fault. Since hearing that I've always followed the wiring diagram in the instructions, there's a couple of configurations they suggest, either fuse the light or install seperate pull switch for the fan.

My Elecsa assessor told me the same story on my last assessment a couple of weeks ago, it's obviously an area they feel needs drumming home.
Funnily enough, I'm currently looking at a job which requires an IPX5 fan in zone 1 (water jets are probable) which the customer insists needs a timer & it's a pain to fuse it down to 3a, especially as there's no void above the light fitting and the wiring is going to have to be surface mounted in trunking.
I'm doing my utter best to find some equipment that neglects to mention or doesn't require any further protection.